1. The Field of the Invention
The present invention relates to equipment for manipulating threaded tubular members and to clamping threaded tubular members and breaking joints between threaded tubular members.
2. The Relevant Technology
The process of drilling, especially in subterranean formations, often involves lifting numerous drill rods into place and then connecting them together. The connected drill rods form a drill string, which is often tipped with a drill bit. The connection between adjacent drill rods is often referred to as a joint. Frequently, the joints between the drill rods are formed when one drill rod with male threads is threaded into engagement with female threads of another drill rod. The joint between the drill rods is often tightened to maximum torque using a clamping and breaking device. During the drilling process, a drill rig applies an axial force and rotates the drill string, often causing these joints to become very tight and possibly require tremendous force to break the joint and separate the drill rods.
When the drill string is removed from the borehole (the hole created during drilling), the entire string of drill rods may need to be removed by tripping the drill string out of the borehole. As this is done, each of the joints for the rods, which now may be extremely tight, are often broken by unthreading the male and female ends of adjacent drill rods. In some instances, multiple drill rods (which are typically around 5, 10, or 20 feet), may be connected to form a string that extends for very long distances. Thus, a single drill string may have hundreds of joints that may need to be broken and separated. The drill rods are often tightened to a torque higher than the torque applied by a drill head. Accordingly, the torque in the joint can be similarly high.
Conventionally, several methods and associated devices have been used to break the connections between the threaded ends of adjacent drill rods. Most of these proposed methods and devices typically employ some form of power-equipped wrench or similar tool to provide the torque necessary to break the threaded connections between drill rods. Typically, two drill rods are threaded (or unthreaded) by holding one drill rod stationary with one of the jaws while the rotating the other drill rod in the appropriate direction using the other jaw.
While such configurations can provide for the breaking of joints, difficulties can still arise from time to time. For example, many tools only provide a fixed or narrow range of gripping diameters, so that the jaws or the entire device must be changed when moving from one diameter to another. Further, some tools provide a fixed axial distance between the jaw sets such that longer or shorter threaded connections cannot be accommodated. In addition, many tools do not provide sufficient frictional contact between the contact surface on the tong dies and the drill rod, causing the drill rods to slip when being threaded or unthreaded and leading to inefficiencies as well as safety hazards. This problem can be exacerbated as the tong dies wear over time. And the slipping itself can even contribute to the wear on the tong dies. Additionally, many current tools are manufactured with tong dies that must be replaced often, resulting in inefficiencies when the drilling operation is halted while the tong dies are replaced.
Another potential difficulty can arise when the tong dies are replaced. For example, in many systems the tong dies can only be replaced when the whole drill string has been removed out of the bore hole. Otherwise, there is not enough room to exchange the tong dies. The resulting risk is that the entire drill string can slip out of the jaws and fall back into the borehole.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced